Mucins are the primary secretory component of salivary mucous glands, such as the major sublingual gland and many' of the minor salivary glands. Protective functions which have been attributed to mucins include: 1) lubrication and hydration of oral surfaces; 2) selection for the adherence as well as clearance of -specific micro-organisms; and 3) modulation of the pellicle lipid content through either covalently-bound fatty acids or through non-covalent, heterotypic complexation. Within mucous glands, mucins are synthesized and secreted by the mucous cell phenotype. The study of the molecular mechanisms which regulate the synthesis and secretion of mucins have been hindered by the cellular heterogeneity of salivary mucous glands which greatly complicates the isolation and study of cell-specific molecules and intracellular reactions. An exception is the guinea pig sublingual gland which-is composed entirely of mucous acinar structures and therefore represents an important potential model to study mucous cell biology unencumbered by other contaminating acinar cell types. We currently are studying the regulation of mucin glycoprotein secretion from acinar structures in vitro derived by enzymatic dispersion of rat sublingual glands. Dispersed: acinar structures are extremely viable and pharmacologically responsive to different secretagogues but are composed of both mucous cells and serous demilune cells. Therefore, we plan to develop a similar in vitro model using guinea pig sublingual glands, We plan-to evaluate the cell model morphologically by light microscopy to determine cell viability and mucous cell composition. Pharmacological studies will be conducted to demonstrate the presence of a regulated muscarinic-cholinergic pathway. Results from these studies will be used as preliminary studies for a formal R01 application with the primary objectives of elucidating components of the intracellular signalling pathways in mucous cells.